Resolved Question: Where to go for pet scan and drug abuse recovery?

I am a first generation immigrant and have no experience or any idea of how to get help for my 21 year old son’s drug and alcohol addiction. 3 months ago he came to me confessing everything: he had been abusing drugs for the past 3 and 1/2 years and that this past school year was the worst. Since then he’s given up everything and been sober. He had been using marijuana, cocaine, mdma, painkillers, alcohol, and cigarettes. Now he is very afraid of them and will never use them again. As much as I’m very glad he’s been sober and is willing to recover and go back to school, he has told me that he’s very scared that it might be too late. He’s been dealing with depression, insomnia, loss of concentration, memory problems (can’t read a book or watch a movie and remember the story days later), inability to communicate clearly what he wants to say in his mind, among other things. I have scheduled a meeting with a psychiatrist for him this week. He insists on getting a pet scan, but feels too anxious and guilty to get one from a neurologist at a regular hospital for he fears they will be judgmental. Is there anywhere to bring him to get a pet scan from a neurologist that understands what recovering “addicts” are going through and is able to tell us how much damage has been done and if there’s anything we can do to recover lost brain activity? Or do most neurologists that give pet scans for cancer treatments and other natural illnesses also deal with drug abusers? Or should we go to a drug addiction specialist and he refers us to a proper neurologist? I will ask the psychiatrist this as well, but just wanted to shoot my question on here for any additional advice. Thank you so much for answering and I very much appreciate it.